Optical trapping of two different microparticles by a double-tapered fiber probe

Abstract

We theoretically and experimentally study the optical trapping of two different microparticles by a double-tapered optical fiber probe (DOFP) which is fabricated by the interfacial etching method. A SiO2 microsphere and a yeast, or two SiO2 microspheres with different diameters, are trapped. We calculate and measure the trapping forces on the two microparticles, discuss the impacts of the geometrical size and refractive index on the trapping forces. Both the theoretical calculation and experimental measurements indicate that if the two particles have the same refractive index, the larger the second particle is, the larger the trapping force is. Whereas, if the two particles have the same geometrical size, the smaller the refractive index is, the lager trapping force is. Trapping and manipulation of different multiple microparticles by a DOFP enhance the application of optical tweezers, especially in biomedical engineering and material science.

Optical manipulation based on fusion spliced all-fiber optical tweezers

“…9 Existing FOTs generally include: (1) trapping particles by the evanescent field of fiber tip near-field optics, including parabolic tips, 10 hollow fiber cone tips, 11 biconical cone tips, etc. 12 (2) Trapping objects using the tightly focused laser beam at the end of the fiber, including dual fiber OTs with flat-end faces, 13,14 dual fibers or multifiber OTs based on hemispherical self-lens end faces, 15 FOTs based on the end-face of Fresnel zone plates; 16 these methods improve the defect of insufficient NA of FOTs and enhance the application scenarios of FOTs. 17 At the same time, some special structures of FOTs have also emerged, such as four-core fiber with ring grooves, 18 graded index (GRIN) fiber tape with a microcavity, 19 OTs of printing metalens on fiber end face, etc.…”